JPS559103A - Level detecter at hopper of unhardened concrete - Google Patents

Abstract

PURPOSE:To obtain a level detecter capable of detecting level of unhardened concrete layer even if its horizontal distance more than ten-odd cm, by monitoring sound pressure of ultrasonic wave generated from the vibrator fixed at the outside face of the hopper, emerging in the prescribed time, being attenuated after making multiple reflection at inner and outer walls of the hopper. CONSTITUTION:Vibrator 2, being connected with oscillator and receiver 3, is fixed at the outside wall of the steel hopper 1, thickness thereof is between several and 10 cm. Electric pressure signal is generated by the pulse-oscillator circuit 7 of the device 3 to the vibrator 2 and ultrasonic wave is transmitted therefrom. This pulsified ultrasonic wave is reflected in multiple ways against th inner and outer sides of the wall 1, attenuated, and the sound pressure being attenuated gradually is received at the receiving circuit 8 thru the vibrator 2, and is delivered to the hold circuit 9, which holds signals being sent from circuit 8 to 9 by the function of the reset siganl generated by the time-setting circuit 6. By comparing by the comparator circuit 10 the received electric pressure being held with the electric pressure which is predetermined by the level-specifying device 13, and if the received pressure is below the prederemined value, the alarm dvice 12 is actuated thru the alarm circuit.